Forms intended for lottery games, surveys and the like have traditionally been read by page scanners, whose mechanical feeding mechanism also flattened the form with the help of rollers and springs before presenting the form to the scanning head. Subsequently, scanning was performed under controlled lighting conditions that disregard a set of colors, termed “blind colors” (e.g., red and its close hues). All the regions that are intended for user markings as well as any information not required to be machine-readable have typically been colored in these blind colors, so that there has been adequate guidance for the user's placement of marks, but the guides themselves remained essentially invisible to the scanning sensor. This eased the user mark detection process. Additional machine-readable indices may have been printed in machine-visible ink along a side of the form, separate from the area allocated to user markings, to help the inference of the possible marking areas (typically arranged in the form of a rectangular grid) by the machine. These machine-readable markings would traditionally allow compensation for the image shift and/or rotation encountered during the scanning process, but would not traditionally convey any other spatial information (e.g. , scaling and/or position in the 3D space).
The traditional page scanner has complex and precise mechanical parts; hence its dimensions are typically dictated by the document size and mechanical complexity, increasing its overall size and manufacturing costs. Additionally, regular maintenance is typically needed, further increasing the ownership cost.
At least in part for these reasons, image sensors have been proposed for the task. Of note, image sensors have been known to be used in the art for reading barcode symbols, but these bar code applications operate under strict printing tolerances for machine printing and offer designed-in redundancy that facilitates reading by such a sensor.
Among those benefits and improvements that have been disclosed, other objects and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying figures. The figures constitute a part of this specification and include illustrative embodiments of the present invention and illustrate various objects and features thereof.